De Waart made his début at the San Francisco Symphony in 1975. A year later, he became principal guest conductor, and from 1977 to 1985 he was music director. From 1986 to 1995, he was music director of the Minnesota Orchestra.

In 1989, de Waart returned to the Netherlands, where he was appointed music director of the Netherlands Radio Philharmonic. He resigned from the post in 2004 and now he is the orchestra's conductor laureate.

De Waart became chief conductor and artistic adviser of the Sydney Symphony Orchestra in 1993. In early 1999, after two successful terms with the orchestra, including taking it on a very well-received tour of the United States, he announced he would be leaving by the end of the year. The orchestra's management was fully engaged in the process of finding his replacement when de Waart changed his mind. He left the post in 2003. While in Sydney, de Waart made no secret of his dislike of the acoustics of the Sydney Opera House Concert Hall, the orchestra's home, saying, "if there is no clear intention to do something to improve the hall, then we really seriously have to look at another venue".[1]

In 2004, de Waart became artistic director and chief conductor of the Hong Kong Philharmonic Orchestra. In November 2007, de Waart and the Hong Kong Philharmonic agreed on a contract extension of his tenure to 2012.[2]

On January 3, 2008, de Waart was named the sixth music director of the Milwaukee Symphony Orchestra, and he assumed the post in September 2009. In March 2008, the Saint Paul Chamber Orchestra announced that de Waart was scheduled to become an Artistic Partner with the orchestra in the 2010-11 season.[3]

On March 10, 2010, de Waart announced he would step down from the post of Chief Conductor and Artistic Director of Hong Kong Philharmonic after the 2011-12 season.[4] A few weeks after that, on April 2, the Milwaukee Symphony Orchestra announced that de Waart had received a contract extension with that organization through the 2016-17 season.[5] Also in April 2010, the Royal Flemish Philharmonic (deFilharmonie) announced de Waart had signed a contract to become its Chief Conductor for six seasons beginning in 2012.[6]

On February 12, 2015, it was announced that de Waart will step down as music director of the Milwaukee Symphony Orchestra after the 2016-17 season. He will retain the title of conductor laureate.[7]

In March 2002, de Waart announced his departure in 2004 as chief conductor of the Netherlands Opera (DNO), a position he filled since 1999. In giving his reason for leaving, de Waart mentioned his desire to spend time with his two small children. However, de Waart also mentioned in an interview with the newspaper Trouw his disagreement with the conceptual staging of Lohengrin by DNO director Pierre Audi and the planned Madame Butterfly of Robert Wilson. De Waart said he missed "humanity" and "emotion in the direction."

In July 2007, the Santa Fe Opera named de Waart their chief conductor, effective 1 October 2007.[8][9] His initial contract was for 4 years. However, in November 2008, SFO announced that de Waart would vacate the position before the end of his contract, no earlier than the end of the 2009 season. de Waart cited health and family reasons for this decision.[10]

De Waart maintains two residences, an apartment in Hong Kong and a house in Middleton, Wisconsin, the hometown of his (sixth) wife, Rebecca Dopp, whom he married in 1999.[13] De Waart and Dopp have two children: a son, Sebastiaan, and a daughter, Olivia. The family left Hong Kong to accommodate their son's asthma.[14]